Drugs with this property are classified, either as blockers of competitive type, if they compete with ACh on cholinergic receptors situated on the post-junctional membrane, or as blockers of depolarizing type, if the neuromuscular block is preceded by depolarization of the membrane. Moreover, agents provided with a combined competitive and depolarizing action are known, even if scarcerly used in therapy.
Drugs provided with skeletal muscle paralysing activity are clinically used, especially in anaesthesiology.
Skeletal muscle paralysing agents of the depolarizing type are mainly provided with fast starting and shortly lasting action. That makes them suitable for many therapeutic uses, even if it is known they may show serious complications, such as arrhythmias, cardiac arrest and, frequently, post-surgery muscular pains, just because of their mechanism of action, which causes muscular fasciculation before the effect of neuromuscular block starts.
The skeletal paralysing agenst of competitive type do not show the unwanted side effects, which may arise when using depolarizing blocking agents, but they are characterized by a slow onset and a long lasting duration of action. Moreover, they could induce unwanted side effects, such as release of histamine, ganglionic block, muscarinic receptor block (mainly, cardiac receptors) and inhibition of the norepinephrine reuptake; which effects could also induce relevant interference with the autonomic control of circulation.